The measurements of coexistence curves and turbidity for {xC6H5CN + (1 − x)CH3(CH2)14CH3} in the critical region
Introduction
There exists an isolated critical solution point at the equilibrium vapour pressure in a binary liquid mixture. Near this critical point, the difference Δρ of a general density variable, between two coexistence phases, the correlation length ξ, and the osmotic compressibility χ exhibit universal power-law dependences on the reduced temperature t {t = |T − Tc|/Tc, where Tc is the critical temperature} near the critical point. These dependences may be described by the following forms:where ρ is the density variable, ρ1 and ρ2 are the values of the density variables in the upper and lower coexistence phases; β, ν, and γ are the critical exponents; B, ξ0, and χ0 are the critical amplitudes that are dependent on molecular mass of chain-molecule component for chain-molecule solutions of both small molecules and polymers [1]. As a continuing part of study of the critical phenomena of binary mixtures of chain molecules in a polar solvent, in this paper, we report the experimental results of the coexistence curves and the turbidity for the system of (benzonitrile + hexadecane). The results are analyzed to obtain the critical exponents and critical amplitudes corresponding to (ρ2 − ρ1), ξ, and χ. The diameters ρd of the coexistence curves are examined to discuss the goodness of the general density variables used to construct the order parameters.
Section snippets
Experimental
The benzonitrile, mass fraction 0.99, obtained from the Shanghai Kaiming Chemical Factory was distilled slowly under reduced pressure. The middle part of the distillate was collected and stored over a 0.4 nm molecular sieve. The hexadecane, mass fraction 0.99, supplied by Fluka Co., was dried and stored over a 0.4 nm molecular sieve.
The coexistence curves were determined by measurements of the refractive indices n of two coexisting phases using a technique of “minimum deviations” The apparatus
Coexistence curves
The critical mole fraction and the critical temperature of {xC6H5CN + (1 − x)CH3(CH2)14CH3} were determined to be xc = (0.673 ± 0.001) and Tc = (304.4 ± 0.2) K, respectively. The refractive indices n were measured for each coexisting phase at various temperatures. The results are listed in columns 2 and 3 of table 1 and are shown in figure 1(a).
In order to obtain the (T, x) coexistence curve, a series of binary mixtures with known mole fractions x was prepared and their refractive indices in the single-
Acknowledgements
This work was supported by the National Natural Science Foundation of China (Projects 20173024, 20273032 and 20473035) and the Key Project of Chinese Ministry of Education (No. 105074).
References (22)
- et al.
Chem. Phys. Lett.
(1998) - et al.
J. Chem. Thermodyn.
(1997) - et al.
J. Chem. Thermodyn.
(1996) - et al.
Physica A
(1991) - et al.
J. Chem. Thermodyn.
(1998) - et al.
J. Chem. Thermodyn.
(1993) - N. Wang, C. Mao, R. Lu, X. Peng, X. An, W. Shen, J. Chem. Thermodyn., in...
- et al.
J. Chem. Phys.
(1999) - et al.
Organic Solvents
(1986) - Thermodynamics Research Centre, API 44 Tables, Selected Values of Properties of Hydrocarbons and Related Components,...
Phys. Rev. B
Cited by (15)
Liquid-liquid equilibrium and heat capacity for the critical binary solution of {n-decane + benzonitrile}
2019, Journal of Chemical ThermodynamicsCitation Excerpt :The binary solutions of {n-alkane + benzonitrile} are favorable for precise studies of the critical behaviors of the coexistence curves by refractive index measurements. In the previous studies we reported the critical properties of a series of binary mixtures of {n-alkane + benzonitrile } [10–18]. As a part of our continuous studies, in this work we report the liquid-liquid coexistence curve and the specific isobaric heat capacity for binary solution of {n-decane + benzonitrile}.
Thermodynamics of mixtures containing aromatic nitriles
2018, Journal of Chemical ThermodynamicsCrossover parametric equation of state for asymmetric binary liquid system
2014, Journal of Molecular LiquidsCitation Excerpt :Fig. 1 shows the coincidence of calculated reduced densities obtained from Eqs. (16)–(18) and (41) and the available data from literature versus reduced temperature. The mean (maximum) deviation (%) between the calculated reduced density difference and the experimental data obtained from Refs. [3,16,19–24] are given in Table 6 which show that deviations are within their stated uncertainty. In this study, the critical behavior of the density like properties was investigated in the framework of the complete scaling formulation for weakly compressible binary liquid mixtures.
Universal critical amplitude ratios in binary mixtures of {benzonitrile + alkane}
2013, Journal of Chemical ThermodynamicsCitation Excerpt :Table 1 lists the purities and suppliers of the chemicals used in this work. The critical compositions were carefully measured by the method of “equal volume” [27,28] for {benzonitile + n-dodecane}, {benzonitrile + n-pentadecane}, {benzonitrile + n-hexadecane}, {benzonitrile + n-heptadecane}, and {benzonitrile + n-octadecane} and are compared with that obtained in measurements of coexistence curves [25,27–29] in columns 2 and 3 of table 2. The results coincide with each other within their uncertainties except for the critical mole fraction of {benzonitrile + n-hexadecane} and {benzonitrile + n-octadecane}, which may be attributed to the different sources of the chemicals used in experiments [31].
The liquid-liquid coexistence curves of {benzonitrile + n-pentadecane} and {benzonitrile + n-heptadecane} in the critical region
2012, Journal of Chemical ThermodynamicsCitation Excerpt :Moreover, as we indicated [9], the contribution of the heat capacity plays an important role in describing the asymmetric criticality within the frame of the complete scaling theory. As a part of the continuous investigations on the critical behavior of the binary mixtures of (benzonitrile + n-alkanes) [10–15], in this paper, we report the measurements of the liquid + liquid coexistence curves for binary solutions of benzonitrile + n-pentadecane and benzonitrile + n-heptadecane. Detailed analysis of the asymmetry of the coexistence curves and discussion about the validity of the complete scaling theory are presented.